Muscle tissue ischemia monitoring using impedance spectroscopy: preliminary animal studies

Tissue ischemia detection can be performed using several methods, however, neither of them is writable for non-invasive, long term, and continuous tissue ischemia monitoring. Tissue impedance measurement presents a simple method for monitoring certain tissue characteristics and it can be used for ischemia monitoring because ischemia of tissues causes changes in tissue impedance. The overall goal of this research is to develop a muscle tissue ischemia monitoring system, based on tissue impedance measurements at various frequencies (impedance spectroscopy). For this purpose, an instrument for complex tissue impedance measurements, over a wide frequency range (10 Hz-1 MHz) was built and tested. The acquisition system uses digital demodulation principles to improve performance, several in-vivo animal experiments were done to obtain data on impedance of healthy and ischemic muscle tissue. The collected data provided the authors with a new knowledge on tissue ischemia-impedance relationship. Also, specific tissue impedance behavior and artifacts were observed. Results indicate that impedance spectroscopy can be used for qualitative ischemia monitoring.